•We fabricated high quantum efficiency Eu2+-doped Ba3Si6O12N2 green phosphors.•We used the two-wavelength excited PL (TWEPL) method to detect NRR centers.•TWEPL: a below-gap excitation light is superposed on an above-gap excitation light.•PL intensity will change when the BGE energy matches optical transitions via NRR.•We detected a distribution of NRR centers in BSON phosphors for the first time.By a conventional solid state reaction method in air and N2/H2 atmosphere, we successfully made two Eu2+-doped Ba3Si6O12N2 (BSON) green phosphors to characterize their nonradiative recombination (NRR) processes. They showed a broad excitation spectrum from 250 to 450 nm which could be efficiently excited by UV or blue LED, and produced an intense broadband emission from 460 to 620 nm. We have clarified a distribution of NRR centers by superposing a below-gap excitation (BGE) light on an above-gap excitation (AGE) light and observing an increase of photoluminescence (PL) intensity. Different BGE effect of two samples implies that the synthesis condition influences the defects in BSON phosphors. Due to the coexistence of the NRR center and trap centers, we obtained a unique behavior of the PL intensity increase as a function of the AGE density.

Nonradiative recombination centers in Si-doped GaAs/AlxGa1−xAs and GaN/InyGa1−yN quantum well (QW) structures were studied by the two-wavelength excited photoluminescence technique. For the former, a pair of trap centers was found in outer Al0.4Ga0.6As barrier layers: one of the pair is attributed to be induced by the diffusion of Si atoms from neighboring Al0.2Ga0.8As barrier layers. In case of GaN/InyGa1−yN, a distribution of traps was detected only inside the GaN layer, which is consistent with previous reports including the yellow luminescent band.

Absence of nonradiative recombination (NRR) centers inside GaAs wells and at GaAs/Al0.2Ga0.8As hetero-interfaces in a Si modulation-doped GaAs/Al0.2Ga0.8As multiple quantum well (MQW) structure became clear for the first time by an improved two-wavelength excited photoluminescence (PL). The NRR parameters of modulation and uniform-doped MQWs were determined self-consistently by combining the analysis of the PL intensity change due to the below-gap excitation with the internal quantum efficiency and the recombination lifetime. These results showed the superiority of modulation-doping scheme over that of uniform-doping for light emitting devices.